Recent Changes Reduce Crashes at 14th and Superior Roundabout

Mayor Chris Beutler today said changes made since October 2013 to the roundabout at 14th and Superior streets have succeeded in reducing the number and severity of crashes at the intersection. The temporary changes at the roundabout will be made more permanent, with concrete curbing replacing temporary markings and traffic control devices. No further changes will be made at this time. The City Public Works and Utilities Department will continue to closely monitor the operation of the roundabout.

Construction began on the roundabout in 2011. It was partially opened in August of 2012, and fully opened in November 2012. This chart shows the difference among three time periods - before the roundabout was built, in its first 11 months of full operation and since the changes were made:

Total Crashes (Annualized)

Percent of Injury Crashes

Average Crash Cost

Jan. - Nov. 2011

27.3

48%

$4,431

Nov. 2012 - Oct. 2013

119.8

19%

$2,284

Oct. 2013-March 2014

40.4

5%

$1,656

"The fact is that roundabout crashes are generally less severe than crashes at intersections with signals," Mayor Beutler said. "The most important effect of the recent changes to the roundabout is the significant reduction in the number of people injured at the intersection. The average crash cost at the roundabout is now 63 percent lower than it was when the intersection was signalized, and the percentage of vehicles that are a total loss has dropped from 19 percent to zero."

The Mayor said the City continues to be concerned that the number of crashes remains higher than it was before the roundabout was constructed. "The majority of the crashes are due to a failure to yield, especially eastbound and westbound," he said. "The main way to reduce the number of crashes is for drivers to slow down, look left and yield to vehicles already in the roundabout," Beutler said.

The changes implemented in October were recommended by a consultant specializing in roundabout analysis and design. The changes included reducing the north-south through lanes from two to one; reducing the east-west through lanes from three to two; installing larger signs; making the street markings more visible; and changing the pedestrian signal from solid green to flashing yellow. Fencing was also installed in February to reduce speeds by limiting sight distances at the approaches to the roundabout.

In terms of traffic flow, a study of the roundabout shows that it operates better than the previous signalized intersection for most of the day. During the morning and afternoon peak traffic hours, the delays are comparable to those of a signalized intersection, with maximum delays of about 90 seconds.